This invention relates to multi-tone jammers and in particular to a digitally implemented device that optimizes the performance of a swept single voltage controlled oscillator (VCO) whereby multiple tones and flatness of tone spectrum are achieved.
The current state of-the-art approach to producing this function is to employ implementations that utilize multiple oscillators which are tuned and adjusted for a spectrum of tones. However, analog sweep generation using R-C time constants will not provide necessary flatness of spectrum or stability of tones when sweeping a single VCO. Tone generation through linear sweep operation of a VCO requires a ramp generation of excellent linearity, fast retrace capability and stable repetitive cycles. These characteristics are noticably improved upon with the digitized sweep generation and modulation provided by the present invention. This approach to implementation of the multitone jammer results in fewer components (oscillators, filters and analog elements) than any previously known design. Also, the requirements for matching phase and amplitude of RF components is eliminated, thereby eliminating the need for adjustments or for critical component selection. The digitally implemented ramp waveform generators that are currently available are not suitable to use as multi-tone jammers. U.S. Pat. No. 3,971,923 entitled "Ramp Function Generator" issued to John L. Linden, July, 27, 1976 illustrates such a device. Ramp function generators of this type generally operate on low frequency (25 Hz) input signals. They cannot achieve the MHz sweep repetition rates necessary for multi-tone generation with a single VCO and appropriate VCO output modulation means are not generally available.